Added missing function.

remoting/protocol/pairing_registry.cc

Index: remoting/protocol/pairing_registry.cc
diff --git a/remoting/protocol/pairing_registry.cc b/remoting/protocol/pairing_registry.cc
index ea8be13f5d8b929d20cded4a2df17cb6a2ad7032..583d84b4e5fc640fba4fe64e23ef9db08904c3da 100644
--- a/remoting/protocol/pairing_registry.cc
+++ b/remoting/protocol/pairing_registry.cc
@@ -56,5 +56,10 @@ std::string PairingRegistry::GetSecret(const std::string& client_id) const {
   return result;
 }
 
+void NotImplementedPairingRegistryDelegate::Save(
+    const PairingRegistry::PairedClients& paired_clients) {
+  NOTIMPLEMENTED();
+};
+
 }  // namespace protocol
 }  // namespace remoting